Facebook’s program looks for positive words like “happy,” “yay” and “awesome,” and negative, or unhappy words, include “sad,” “doubt” and “tragic.” Some not-too-surprising findings: Its gross national happiness index spikes on holidays like Thanksgiving and Christmas. Barack Obama’s election was more than twice as happy as the average Wednesday.

There are a few independent projects like Twendz and Tweetfeel that are exploring the same concept with Twitter. Two Vermont statisticians are harnessing tweets to create a “hedonimeter” that will be released soon at onehappybird.com. Others are exploring building businesses around sentiment analysis — particularly for companies that want to know how the public thinks about their brand in real-time. Pepsi, in fact, does this by collecting tweets mentioning the brand and tracking sentiment changes week by week.